Reduced trapezius pressure pain threshold in fibromyalgia and opioid use.

While opioid medications are potent analgesics, their usage in chronic pain conditions can paradoxically result in opioid-induced hyperalgesia (i.e., enhanced pain sensitivity). However, among individuals with chronic pain, minimal research has examined the effects of long-term opioid medication on pain sensitivity. To better understand how long-term opioid use impacts pain sensitivity, we measured pressure pain threshold (PPT) of the bilateral trapezius among three cohorts: pain-free controls, individuals with fibromyalgia who were not taking opioids (FMN), and individuals with fibromyalgia who were taking opioids long-term (FMO) (NCT05905419). Across these 3 groups, we also measured depression (BSI-18) and fatigue (PROMIS) to examine their relationships with pain sensitivity. Compared to the control group, dominant-side PPT was significantly reduced in both FMN (p = 0.015) and FMO groups (p = 0.004). However, PPT did not significantly differ between FMO versus FMN groups (p = 0.500). Across the fibromyalgia groups, depression and fatigue were not significantly correlated with PPT. From a co-variate analysis and its associated sensitivity analysis, the results did not change when controlling for age, self-identified race, self-identified ethnicity, and BMI. From an exploratory analysis of the FMO group, individuals who took their last opioid medication dose more recently prior to PPT assessment had higher PPTs (i.e., lower pain sensitivity, p < 0.001). In summary, reduced PPT appears to occur similarly across individuals with fibromyalgia regardless of long-term opioid use status; meanwhile, short-term (i.e., more acute) opioid dose timing- related effects on PPT may occur in individuals with fibromyalgia taking opioids long-term. PERSPECTIVE: Compared to pain-free controls, we identified significantly lower pressure pain threshold (PPT) in individuals with fibromyalgia. When comparing individuals taking opioids versus not, PPT was similar across groups regardless of opioid use status. Among the opioid-taking individuals, we identified potential opioid-related effects of PPT increase with more recent opioid dose.